The invention relates to a static power converter, notably for an uninterruptible power supply system, comprising a conversion circuit having a plurality of power semi-conductors, a control board for controlling the semi-conductors of the conversion circuit, and means for supplying electrical power to the control board.
The problems encountered in operation of a static converter involve transmission of the electronics control data at a low level to the conversion circuit power semi-conductors, notably the thyristors of a battery charger, or the transistors of an inverter stack. The conductors carrying this data are subjected to common mode disturbances due to the sudden potential changes of the semi-conductors which they control, when the latter become conducting or blocking. These disturbances can affect the operation of the control boards. A solution to minimize the influence of these disturbances consists in limiting the current flow by inserting a compensating coil between each power semiconductor and the control conductors involved on the board. The inductance achieved does not affect transmission of the useful signals, but prevents currents of the same instantaneous value flowing on two wires.
A wide range of current compensating coils with different current intensity and impedance characteristics are available in the trade. These coils come in the form of individual components having connecting lugs which have to be soldered into the circuit. A conversion circuit of a static converter has a certain number of power semi-conductors, and the range of an uninterruptible power supply system moreover involves different power levels (for example 10 kVA, 20 kVA . . . 80 kVA). There must be a predetermined compensating coil impedance to correspond to each power and each type of conversion circuit. It can be noted that a multitude of compensating coils would be required to obtain efficient attenuation of the noise generated by operation of the converter. Furthermore, individual soldering of these coils complicates manufacture of the converter.
The object of the invention consists in simplifying the noise suppression operation of a static power converter.